antekboodzik
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Detailing renaissance lute rosette
Hi, help me please to manage with some issues regarding finishing lute rosette.
What it is, it is a belly for my second instrument. I decided to prepare rosette pattern in Inkscape software (this is very easy using clone tool). I
also prepared simple tool for piercing wood from long scalpel blade by filing its tip gently on a diamond file and stropping to produce a kind of
mini-chisel. I have just finished removing away "holes", at least as much accurately as I could do. And the hardest part of embossing acanthus stems
and leaves over geometric bars is in front of me. Here are a few things I am unsure:
1. I have glued printed pattern to "inner" surface of the belly, in place prepared by thinning it down to about 1 - 1.4 mm, and do piercing work from
there. But over the Internet you can see that many luthiers do it contrary, from the top, and then remove paper... Which method is better?
2. I used a very little of ordinary mucialge to glue the pattern, and it quickly started to peel off. Shall I remove it by all, leave as it is or
maybe paint again with glue to put it back as a reinforcement?
3. I plan to do carving work with scalpel too. But I found that cutting e. g. small edge at angle of about 45 degree cross-grain extremely difficult.
Even scalpel baldes are very sharp, its tends to "dig" in wood and chip hard winter grains from between soft ones, leaving small "teeth" especially on
narrow elements. Maybe scalpel blades are not stiff enough?
4. How outside, narrow circles around rosette are cut? The line can be scribed with circle cutter, but hov to make it V-shaped or U-shaped?
Any suggestions are hereby welcome 
[file]34415[/file]
[file]34426[/file] [file]34432[/file] [file]34428[/file] [file]34430[/file] [file]34424[/file]
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jdowning
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See here for how I cut/carve a lute rosette. In this case I detailed the face of the rosette with a branding iron whereas normally I would cut this
detail with a scalpel giving better (and more authentic!) results than burning in my opinion.
http://www.mikeouds.com/messageboard/viewthread.php?tid=8488&pa...
To summarise the sound board must be thinned over the area of the rosette to about 1 mm thick. The transition from the full soundboard thickness must
be smooth (not abrupt as you have made yours).
The paper pattern (with a border) is glued to the underside of the sound board with thin hot hide glue and ironed in place with a hot iron. The paper
pattern must remain in place and provides needed reinforcement of the completed rosette (in addition to mini reinforcement braces).
The centre of the rosette should be pierced right through with a pin for reference and the exact outside diameter diameter of the rosette marked
lightly in pencil on the face of the sound board with a compass. This area is then coated with shellac varnish to harden the wood surface and
reinforce the rosette during cutting.
The sound board must be placed face down on a hard cutting surface such as smooth fibre 'hardboard' or 'Masonite'. The cutting surface must not yield
under the cutting forces.
The rosette pattern is then pierced through the paper with fine chisels that must be kept razor sharp with a leather strop throughout the whole
process. Surgeon's scalpel blades may be sharp enough to start with but craft blades may not so should be sharpened and honed before use. Pierced
cutting should be undertaken starting at the centre of the rosette and working outwards.
The outside face of the rosette may then be carved with incised 'V' cuts made with a scalpel. Mark the cut positions and lines lightly with a pencil
to avoid mistakes when carving. The cuts will penetrate to about half the depth of the wood and should be made with a number of repeated light passes
to achieve full depth. Do not try to cut full depth in one pass.
Finer detail may be gently carved with a scalpel or just left alone if you do not have a steady hand and good eyesight. If you break some of the fine
detail just glue it back in place.
Any little 'whiskers' of wood left in the open holes of the rosette may be 'cleaned up' with a scalpel blade working from the paper side or just left
as is. Do not use files for this work.
In your case I would re-glue the paper pattern where it is peeling away and shellac the outside face of the rosette before carving the incised
detail.
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antekboodzik
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Shall I apply shellac with a cloth/pad or better use a soft brush?
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jdowning
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A small soft artists brush would be easier to control and would not risk breaking the delicate carving as a cloth or pad likely would. Shellac making
its way into the holes in the rosette would not be a bad thing as it would soak into the edges of the wood adding further strength to the detail
carving.
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antekboodzik
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Here's the result  At least better as in my first time.
However, great tip with that shellac. It slightly hardened summer grow rings (compared to winter ones), and make the carving much more
controllable.
Another question is gluing supporting bars in a way they conform the differences in top thickness. I plan to shave shorter bars to fit in the "dip" of
rosette area, and glue a thin, fitted strip in the middle of one longer, which will be in the centre of the rosette.
I am going to put a gentle coat of shellac sealer on this top. I think the rosette should be shellac-ed prior to gluing supporting bars, leaving them
unfinished. Good idea or not? Also, paint the bars black before gluing in order to make them hardly visible? Many do this, but several makers
don't.
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jdowning
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Nice work!
Usually there should be a border around the paper rosette pattern and the little support bars under the rosette carving would extend to the edges of
the border - say an extra 5 mm each side of the rosette. This provides additional strength to the reinforcement but is not a particularly critical
requirement I suppose. Providing a thin levelling strip or shim under the central bar that will run the full width of the sound board should work
satisfactorily.
I don't paint the rosette support bars black as the bars - when left unpainted - are hardly visible as they are shallow in depth and are positioned
under the rosette where they are mostly covered by the carving - for example directly underneath those two horizontal cross pieces forming the 'Star
of David' component of the design.
I would shellac the face of the rosette after fitting the little braces but it should not really matter either way. No doubt you will apply this
'water thin' dilute sealing coat for the sound board with a cloth pad so be sure to avoid the rosette otherwise you will risk breaking the delicate
carving. Any additional shellac on the rosette should be gently applied with a soft brush as before.
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